An optical coupling device such as an isolation amplifier is generally used in a circuit for driving a power semiconductor element such as an insulated gate bipolar transistor (IGBT). The optical coupling device generally includes a light-emitting element, a transmission integrated circuit (IC), and a receiving IC. When the light-emitting element emits an optical signal based on an electrical signal output from the transmission IC, the receiving IC receives the optical signal and converts the optical signal into an electrical signal for output.
One of main characteristics of the optical coupling device described above is an offset voltage. The offset voltage is a non-zero voltage output when an input signal is zero. For this reason, the output is set to zero when the input is zero by correcting the output voltage when using the optical coupling device. However, the offset voltage changes depending on temperature which makes correction difficult. The offset voltage temperature variability can be affected by the magnitude of the offset voltage, such that it is desirable to reduce the magnitude of the offset voltage so as to suppress variation within the expected temperature change range.